21049911 has 12 divisors (see below), whose sum is σ = 31454280. Its totient is φ = 13549200.

The previous prime is 21049907. The next prime is 21049939. The reversal of 21049911 is 11994012.

It is not a de Polignac number, because 21049911 - 2² = 21049907 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21049711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40065 + ... + 40586.

It is an arithmetic number, because the mean of its divisors is an integer number (2621190).

Almost surely, 2^21049911 is an apocalyptic number.

21049911 is a deficient number, since it is larger than the sum of its proper divisors (10404369).

21049911 is a wasteful number, since it uses less digits than its factorization.

21049911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80686 (or 80683 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 21049911 is about 4588.0181996152. The cubic root of 21049911 is about 276.1108171884.

The spelling of 21049911 in words is "twenty-one million, forty-nine thousand, nine hundred eleven".